The Buddha said to enjoy happiness ourselves we must strive for the happiness of others.
These farm animals, in particular the goats, cats and German Sheppard, require a certain amount of attention each day. They experience loneliness, boredom, fear, anxiety just as we do because they share our very same nature.
While looking after the farm while Osaek was at his new job, I enjoyed taking Pata for long walks deep in the woods, exploring the full breadth of our property and beyond. Letting her free of the cage each day and seeing her bolt off into woods was a treat. I'm too slow for her, but she always stayed with me, running ahead and back and all around. Seeing her in fully her element, clearly happy, made me happy as well.
In my experience it's easier to see the true nature of an animal than a person, simply because it's easier to put aside those habits which reinforce a sense of self. With animals its effortless to instead just be present, content in the absence of thought or speech, nevertheless taking care of all things spontaneously as they arise. Curiously, I don't believe we can directly see another’s Buddha nature, in truth we can only ever see our own. This of course is the point of the koan, but caring for animals can only help with this and is just generally a good practice.
We still need to find some balance that maximizes both freedom and safety for all our animals, having more people here would certainly help with this.